Coverings for architectural openings such as windows, doors, archways and the like have assumed numerous forms for many years. Early forms of such coverings consisted primarily of fabric draped across the architectural opening, and in many instances the fabric was not movable between extended and retracted positions relative to the opening.
Retractable coverings for architectural openings, herein referred to as shades, have evolved into many different forms, which include roller shades in which a piece of flexible material can be extended from a wrapped condition on a roller to an extended position across the architectural opening, and vice versa. Other popular forms of retractable coverings for an architectural opening include Venetian blinds, vertical blinds, cellular shades and various variations on these basic designs. Cellular shades, as opposed to roller shades, generally collapse and stack up when retracted, and expand or extend when in the extended position.
Typically, shades of virtually any type may be manually retracted and extended by the user. More recently systems have been developed to automatically retract and extend shades. These automatic systems employ motors and various counter techniques to determine the position of the shade, and its direction of motion.
One issue with current automatic apparatus and methods for monitoring and controlling is that they may not accurately indicate the position of the window covering when being extended. Also, they also may not effectively indicate when the shade is obstructed during its downward motion.
It is to satisfy the above-recognized issues that the present invention has been developed.